Local area network systems, such as Ethernet systems, have become popular in both office and industrial environments. Such systems use bus structured architectures which allow a plurality of nodes to communicate across the area network. The communications are transmitted across such cables as coaxial, fiber optic and shielded twisted-pair.
Because of the critical nature of communication between devices in certain applications, such as in the process industry, it is often necessary to provide redundant communications media to insure communications in the event that one communication path fails. In systems such as Ethernet systems, redundant communication paths are feasible only if all communications nodes contain at least one Ethernet controller for each communication path, and if the nodes have routing capability. Routing capability is a protocol which requires each node to make decisions about which path to use for communication with an adjacent node. In existing systems, not all nodes are capable of routing, and many do not support multiple Ethernet interfaces.
Therefore, a need has arisen for a method and apparatus that allows devices without routing capability and those without sufficient communication controllers to be adapted to communicate over redundant paths.